#ifndef PID_v1_h
#define PID_v1_h
#define LIBRARY_VERSION	1.0.0

class PID
{


public:

  //Constants used in some of the functions below
#define AUTOMATIC	1
#define MANUAL	0
#define DIRECT  0
#define REVERSE  1

  //commonly used functions **************************************************************************
  PID(double*, double*, double*,        // * constructor.  links the PID to the Input, Output, and 
  double, double, double, int);     //   Setpoint.  Initial tuning parameters are also set here

  void SetMode(int Mode);               // * sets PID to either Manual (0) or Auto (non-0)

  bool Compute();                       // * performs the PID calculation.  it should be
  //   called every time loop() cycles. ON/OFF and
  //   calculation frequency can be set using SetMode
  //   SetSampleTime respectively

  void SetOutputLimits(double, double); //clamps the output to a specific range. 0-255 by default, but
  //it's likely the user will want to change this depending on
  //the application



  //available but not commonly used functions ********************************************************
  void SetTunings(double, double,       // * While most users will set the tunings once in the 
  double);         	  //   constructor, this function gives the user the option
  //   of changing tunings during runtime for Adaptive control
  void SetControllerDirection(int);	  // * Sets the Direction, or "Action" of the controller. DIRECT
  //   means the output will increase when error is positive. REVERSE
  //   means the opposite.  it's very unlikely that this will be needed
  //   once it is set in the constructor.
  void SetSampleTime(int);              // * sets the frequency, in Milliseconds, with which 
  //   the PID calculation is performed.  default is 100



  //Display functions ****************************************************************
  double GetKp();						  // These functions query the pid for interal values.
  double GetKi();						  //  they were created mainly for the pid front-end,
  double GetKd();						  // where it's important to know what is actually 
  int GetMode();						  //  inside the PID.
  int GetDirection();					  //

private:
  void Initialize();

  double dispKp;				// * we'll hold on to the tuning parameters in user-entered 
  double dispKi;				//   format for display purposes
  double dispKd;				//

  double kp;                  // * (P)roportional Tuning Parameter
  double ki;                  // * (I)ntegral Tuning Parameter
  double kd;                  // * (D)erivative Tuning Parameter

  int controllerDirection;

  double *myInput;              // * Pointers to the Input, Output, and Setpoint variables
  double *myOutput;             //   This creates a hard link between the variables and the 
  double *mySetpoint;           //   PID, freeing the user from having to constantly tell us
  //   what these values are.  with pointers we'll just know.

  unsigned long lastTime;
  double ITerm, lastInput;

  unsigned long SampleTime;
  double outMin, outMax;
  bool inAuto;
};
#endif


